Voyager 1 officially leaves Solar System.

[Iroscato]

http://m.bbc.co.uk/news/science-environment-24026153
So it's finally been confirmed, Voyager 1 is now in interstellar space, the first man-made object to achieve such an amazing feat. This is awesome.

[Napoleon the Clown]

I think I speak for all of us when I say: Fuck yeah.


Now the question is, will it have power when it gets far enough away from the sun that we can say it's effectively out of the gravitational field? I'm fully aware that the sun's gravity will technically influence it in some minute way, but there's gonna be a point where the gravity reaching it from the sun is effectively nil. I'm gonna guess the power will die before that happens, but I could be wrong and the influence from the sun doesn't extend as far as I think.

[energiewende]

Not that it's new, but deserving a repost:



Earth as seen from Voyager 1 (the slightly brighter spec in the lower right).

[Simon_Jester]

I think I speak for all of us when I say: Fuck yeah.


Now the question is, will it have power when it gets far enough away from the sun that we can say it's effectively out of the gravitational field? I'm fully aware that the sun's gravity will technically influence it in some minute way, but there's gonna be a point where the gravity reaching it from the sun is effectively nil. I'm gonna guess the power will die before that happens, but I could be wrong and the influence from the sun doesn't extend as far as I think.

Define "effectively nil" in a rigorous fashion, and I'll give you an answer.

Not that it's new, but deserving a repost:

http://upload.wikimedia.org/wikipedia/c ... ue_Dot.png

Earth as seen from Voyager 1 (the slightly brighter spec in the lower right).

Now now, that was taken in 1990, when she was only forty AU out. The Voyagers are now about three times that far away.

[Napoleon the Clown]

I'm not an astro-physicist, how can I know these things?

Gravitational dominance. I actually bothered to read some stuff and that's way beyond what Voyager's power supplies will last for. Something in the order of 1 light year, I think. I'd go out on a limb and say that the Oort cloud counts as being influenced by the sun. Since it's orbiting it.

[GrandMasterTerwynn]

I'm not an astro-physicist, how can I know these things? :P

Gravitational dominance. I actually bothered to read some stuff and that's way beyond what Voyager's power supplies will last for. Something in the order of 1 light year, I think. I'd go out on a limb and say that the Oort cloud counts as being influenced by the sun. Since it's orbiting it.

The glib answer to the question of "when did the Sun stop having gravitational influence on Voyager 1" is March 5, 1979, when its flyby of Jupiter gave it enough of a velocity boost to exceed the escape velocity of the Sun (thus defining "gravitational influence" as "keeping it gravitationally bound to the solar system.") Its encounter with Saturn a year and a half later just made that difference in velocity greater.

[Terralthra]

The simplest answer I can think of is "the point at which the sun has no greater gravitational influence on Voyager 1 than any other stellar object", and the answer to that is that the closest object of comparable mass magnitude is Proxima Centauri, at 4 light-years away. Were Voyager 1 headed there, and were it the same mass as the sun, their gravitational pull would equal halfway there, when Voyager 1 is 2 LY from the Sun.

Voyager 1 is on an approximate heading of 17h right ascension, -8 degrees declension, and Proxima Centauri is at 14h39m right ascension, -60 degrees declension. Proxima Centauri is approximately 1/10th to 1/8th of a solar mass. The math here is left as an exercise in basic trigonometry.

Barnard's Star, is closer to Voyager 1's vector (17h57m right ascension, +4 degrees declension; .144 solar masses), but further away (nearly 6 LY) and is likewise is a small red dwarf. Wolf 1061 (V2306 Ophiuchi) is even closer (16h, 30m right ascension, -12 degrees declension), further away (13 LY) and similar size (red dwarf).

There aren't any stars closer to Voyager's trajectory that are any closer or bigger than those, and I think it mathematically unlikely that Sol will not be the largest single source of gravitational pull on Voyager 1 for at least 2-3 light years on its current trajectory. At some point before that, it will no longer be the majority gravitational pull, but will still be the plurality.

[Napoleon the Clown]

Asking questions leads to learning! If I decide to figure out what the distances needed are I'd need to refresh my memory on the exact figures for calculating a body's gravitational pull on another object, but that's easy math. Short answer was about what I figured: It will go dead long before it's beyond the sun being the strongest gravitational pull.

Though the glib answer still amuses me.

[PainRack]

I know this forum frowns at me-too posts but 17 hours at light speed........ Wow.........

Also, would anyone more familiar with the subject educate me regarding this xkcd comic?
http://xkcd.com/1189/

Number of times Voyager left the solar system....???

[Terralthra]

PainRack - it depends entirely on how you define "the solar system." Termination shock is where the speed of the solar wind falls below local speed of sound. Heliopause is where the pressure of the solar wind no longer exceeds pressure of the interstellar medium. The heliosheath is roughly between those two areas - after it falls below local speed of sound, but still there enough to interact with the interstellar medium. The heliosphere in general is the region dominated by particles expelled by Sol. The Oort void is potentially referring to the region beyond the Oort cloud. All the other references in the alt text are jokes (mostly puns related to actual stellar phenomena).

[Borgholio]

Go V'ger, go!

As far as how we define solar system, I wonder if it's a bit excessive to consider the Oort cloud part of the solar system, seeing as how it is only *barely* affected by our sun's gravity field.

[Napoleon the Clown]

From what I understand, the majority of the Oort cloud is actually in orbit of the sun.

[Borgholio]

Right, it's in the gravitational sphere of influence, but obviously NASA doesn't seem to consider that to be the criteria for being part of the solar system, even though it still orbits the sun...

[Napoleon the Clown]

The definition of solar system is... messy.

[Irbis]

There aren't any stars closer to Voyager's trajectory that are any closer or bigger than those, and I think it mathematically unlikely that Sol will not be the largest single source of gravitational pull on Voyager 1 for at least 2-3 light years on its current trajectory. At some point before that, it will no longer be the majority gravitational pull, but will still be the plurality.

If we map distance between Barnard's Star and Sun into 100 cm line (1 SI metre) Voyager 1 travelled about 0.33 of a millimetre. Kind of puts things into different perspective, doesn't it.

[Simon_Jester]

On the other hand, it's kind of impressive that it's even made it a distance that would be visible on that line, if you ask me.

[Irbis]

If you can spot dot 1/3 mm across, you either have good eyes or magnifying glass

[Channel72]

All the other references in the alt text are jokes (mostly puns related to actual stellar phenomena).

The "crystal sphere of fixed stars" refers to Medieval cosmology, actually. Which is pretty funny.

[Simon_Jester]

If you can spot dot 1/3 mm across, you either have good eyes or magnifying glass

Have you looked at a ruler recently? The gradations between millimeters are about far apart; you can see them just fine.

Then again, I suppose I'm actually thinking of a line of such width, and I do have pretty good vernier acuity. But then, who doesn't?

[Highlord Laan]

I thought Pioneer 10 was first out of the system?

[GrandMasterTerwynn]

I thought Pioneer 10 was first out of the system?

No.

Voyager 1 actually caught up with Pioneer 10 in 1998, and then zipped right past it on the order of 1.02 astronomical units per year. The extra gravity assists that Voyager 1 got from Saturn (and Titan,) were substantial. Pioneer 10 only had a Jupiter flyby.

[Crown]

The definition of solar system is... messy.

Indeed!